JPS60242860A - Molding of blood pump - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a blood pump for an artificial heart, and more particularly to an improvement in a sac-type blood pump driven by fluid pressure.

BACKGROUND OF THE INVENTION In recent years, progress has been made in the development of artificial hearts to supplement and temporarily replace the functions of the heart outside the body during targeted surgeries and other surgeries.

Research on a sac-type artificial heart driven by fluid pressure is being conducted in Japan ahead of the rest of the world, and the world's first long-term survival record using goats has shown extremely good results exceeding 300 days. As a result, the path to actual clinical application for patients is about to be opened. A particular problem in the clinical application of artificial hearts is the problem of thrombus formation inside the artificial heart. How to impart antithrombotic properties is an extremely difficult problem, and depends on the material, pump design, surface smoothness, roughness of the blood pump during operation, and even the blood flow pattern inside the blood chamber. It is thought that the problems are involved in a complex manner.

The present invention was developed with particular attention to the deforming behavior of the blood chamber of a sac-type blood pump and the flow of blood within the blood chamber.

Figures 1 to 4 show the basic form of a known sac-type blood vessel and blood chamber, and Figures 5 and 6 show the deformation state of the blood chamber as the fluid pressure is adjusted. It shows.

A sack-type blood pump consists of a pressure-resistant (for example, made of polycarbonate or polyurethane) housing outer case 1 and a flat bag-shaped blood chamber 2 that is secretly housed within the housing outer case. A blood inlet pipe 3 and a blood discharge pipe 4 are formed facing upward and substantially parallel to each other in communication with the blood chamber, and a flange 5 is provided around the upper part of the blood chamber part. The flange portion securely accommodates the blood chamber within the housing outer case. Although not shown, a known valve is installed inside the blood inlet tube 3 and the blood outlet tube 4 to prevent backflow of blood. The introduced blood is pumped out from a blood discharge tube 4.

Blood is pumped out by alternately introducing and discharging fluid through the boat 8 provided at the bottom of the housing outer case 1, and the blood chamber repeatedly expands and contracts as the external pressure of the blood chamber changes. It is what is done.

Problems to be Solved by the Invention The present invention is based on a detailed long-term animal experiment using goats using the sac type artificial heart described above, and a practical test of the thrombus formation conditions in the blood chamber 2 and the durability of the pump. This was obtained as a result of research and development of a blood pump that can be used for a long period of time without causing thrombi in the blood chamber 2.

According to research conducted by the inventor, the locations where blood clots are likely to occur have been determined in animal experiments, and within the blood chamber 2, thrombi are not likely to form near the blood inlet tube 3 and blood outlet tube 4. Very little, the bottom of blood chamber 2,
It was found that blood clots were particularly likely to occur on both sides near the bottom (on the opposing narrow side sides).

The inventors further studied and observed the causes of this phenomenon, and found that in areas where blood flow is comparatively fast, thrombus formation is extremely small, but where blood flow stagnates to some extent, thrombus formation occurs. I also learned that there is a high possibility of this happening. This is because the vicinity of the conduit is a place where blood flows in and out rapidly, and the flow of blood is fast, so there is very little thrombus formation.

It has been found that blood tends to accumulate near the bottom of the one-sided liquid chamber 2.

The inventors of the present invention have conducted various studies on how to eliminate as much as possible the stagnation of blood near the bottom of the blood chamber 2, where blood tends to stagnate as much as possible, and have finally arrived at the present invention. This method was successful in preventing the formation of blood clots.

The thickness of the peripheral wall of the conventional blood chamber 2 is approximately uniform as illustrated in FIGS. When compressed by the pressure of Figure 5A
The volume changes from to B.

FIG. 5A shows the state of change when positive pressure is applied within the housing outer case 1 to the unloaded state shown in FIG. According to this, the volume reduction in the blood chamber 2 does not occur uniformly depending on its cross-sectional shape, but the change in the part that is most likely to change, that is, the center part of the side surface of the blood chamber 2, This occurs preferentially, and under such changing conditions, a decrease in volume due to an increase in pressure propagates to the surroundings. When further pressure is applied, as shown in FIG. 5B, the parts that are most susceptible to change first come into contact with each other, and this contact gradually spreads upward and downward and horizontally. As a result, the blood in the upper part is pushed out directly toward the blood discharge pipe 4, but the blood in the lower part flows along both sides, where it is likely to stagnate. In addition, it is difficult to crush the periphery of the blood chamber 2 by using only air pressure, for example, due to the drag force of the elastic peripheral wall, and as a result, there are areas near the bottom and on both sides that are not in close contact with each other (see Fig. 5, B1, Fig. 6). ) occurs.

Naturally, the degree of blood retention near the bottom and on both sides is greater than that at the center where both side walls contact each other due to complete compression and are crushed. Furthermore, when the pressure inside the housing outer case 1 is reduced and the volume expands as shown in FIG. 5C, this portion is not easily replaced with blood newly introduced at each pulsation.

In fact, as a result of animal experiments, thrombus formation is often observed in the areas indicated by the cross lines in Figure 2.

Therefore, in order to suppress the formation of blood clots,
It has been found that when the blood chamber 2 is compressed, it is best to compress it so that as much as possible, from the bottom end to both sides, there are no unattached parts left.

Means and operation for solving the problem The present inventors have disclosed that, for example, the blood chamber 2 is
It has also been found that when the material is compressed and the volume is reduced, the compression occurs from near the bottom, and the reduction in volume accompanying the compression propagates from near the bottom.

Various methods or structures can be considered as means for obtaining the compression volume change pattern, but in order to achieve the purpose while keeping the basic shape of the blood chamber 2 as it is, conventionally, the blood chamber 2 has been formed substantially uniformly. It was discovered that the most reliable and effective method was to vary the thickness of the surrounding wall of the chamber. Therefore, we continued to study various ways to give the desired taper to the film thickness of the blood chamber, and discovered a new molding method. A four-slash molding method in which a mold is capped in a liquid-tight manner, polychlorinated plastisol is added into the mold to the extent that it contacts the upper lid part, and then a blood chamber is integrally molded by heat transfer from the outside of the mold. In this step, a heat insulating material is placed on the outside of the mold, and at least a portion of the blood chamber is covered with a taber.
The present invention relates to a method of molding a blood pump by thinning it into a shape.

The present invention relates to an improvement in blood pump molding by a slush molding method using a plasticizer and a plastisol of polyvinyl chloride, so-called PVC paste. It is now possible to attach freely.

The PVC paste used in the present invention refers to a product in which ultrafine particles (~1μ) of polyvinyl chloride are uniformly dispersed in a plasticizer such as dioctyl phthalate to form a uniformly dispersed sol with an appropriate viscosity. Compared to the particles of vinyl, which are over 100 microns, the particles of the resin for PVC paste are extremely small. The present invention relates to a method for molding a vinyl chloride blood pump by improving slash processing. The principle of PVC paste processing is to bring the PVC paste into contact with a mold (or resin mold) with a certain heat capacity,
The plasticizer is infiltrated into the PVC particles in the sol by the heat of the contact area, plasticizing it and forming a semi-gel-like film on the surface of the mold.In this state, the mold is coated with PVC paste. When removed from the sol, a gel-like film of soft vinyl chloride having a certain thickness can be formed around the mold. This is further cured to form a uniform resin film. In this case, the thickness of the film is basically determined by the viscosity of the paste sol, the heat capacity of the mold, and the contact time between the mold and the PVC paste crane.If the molding conditions are constant, the film thickness can be easily set to a specified thickness. You can.

The molding method of the present invention will be explained with reference to FIG. 7.8.

First, a known dipping method (for example, Japanese Patent Application Laid-Open No. 57-999
Step 65) creates the upper lid part of the pump (Fig. 7). The conduit portion 3.4 of the upper cover may be provided with an annular projection for attaching the valve, or the conduit element to which the valve is attached may be connected later. In any case, the upper lid part has an upper lid 5 and two blood drainage and introduction conduits 3.4. In this example, a flat cylindrical portion 9 is integrally molded on the inside of the top lid. The upper lid portion thus produced is placed in a metal mold 15 prepared in advance so as to fit exactly into the outside of the cylindrical portion 9 as shown in FIG. 8(A). In this case, the mold 15 is liquid-tightly fitted to the upper lid 5. Next, as shown in FIG. 8 (B1), polyvinyl chloride plastisol (for example, Zeon 131 A manufactured by Nippon Zeon ■) is added to the mold 15 up to the portion indicated by the broken line in the figure. The mold 15 is then immersed in a heating bath. In this case, the heating temperature is 80°
C to 180C, more preferably between 90C and 140C. When the polymer used for plastisol is not a vinyl chloride homopolymer but a copolymer with a low thermal softening point, such as vinyl chloride-vinyl acetate or vinyl chloride-vinyl ether copolymer, a relatively low temperature softening point may be used. The treatment time should be from a few minutes to 30 minutes. If the heating is insufficient or the treatment time is too short, the gelled layer will be too thin. Conversely, if the temperature is too high or the treatment time is too long, the gelled layer will be too thin. 0 Plastisol is too thick and undesirable. The part of the plastisol that comes into contact with the metal mold gels due to heat, and as shown in Figure 8 (C1), a gel layer 16 adheres to a certain thickness. Plastisol also exists inside the molded cylindrical part 9, but the sol in this part does not gel due to the heat insulating effect of the cylindrical part.Therefore, the plastisol in this part is as shown in FIG. 8(D). The paste flows naturally during the paste discharging process, and due to its flattening effect, the entire blood chamber can be finished with a seamless free surface without any steps or seams. Heat curing is carried out.The preferred temperature range at this time is 160 to 240°C, more preferably 190 to 210°C.Curing is insufficient at lower temperatures than 160°C, and thermal decomposition of the polymer occurs at temperatures higher than 240°C. There is a risk that this may occur.

Thereafter, when the mold is cooled and the mold is released as shown in FIG. 8(F), the upper lid portion provided with the conduit and the blood chamber portion can be integrally molded seamlessly.

Now, the present invention was developed by the inventors using the partial insulation method (PT method).
In the slush molding method, when the paste sol is heated to gel, an appropriate heat insulating material is attached to the outside of the mold (the side that comes into contact with the heating medium), and the The present invention was developed based on the idea of a method of continuously thinning the gelled layer of the paste sol in the area where the heat insulating material is attached by interfering with heat conduction.

The present invention will be explained below based on the accompanying drawings.

A first example of the present invention is shown in FIG. 9. In this example, the lower half of the mold 15 is tightly covered with a heat insulating material 16. After filling the inside of the mold with paste sol, when it is immersed in a heating medium, the part where the insulation material is placed blocks the conduction of heat, so there is less heat transfer to the paste sol inside, and the inside of the mold is heated. The thickness of the attached semi-gel film also becomes thinner. Since the mold itself is originally a good conductor of heat, the amount of heat from the part of the mold near the upper end of the heat insulating material that is in direct contact with the heating medium without any heat insulating material is transferred appropriately. There is no difference in thickness between the insulation and the insulation material. If desired, the thickness of the heat insulating material can be changed or a heat insulating material with better heat insulating properties can be used to change the degree of taper of the wall thickness.

FIG. 10 shows a second example of the present invention. This is an example where you want to make the taper even tighter (and preferably even thinner near the bottom of the blood chamber. In this example, the heat insulating material 16 is placed almost in the lower half of the mold 15, and the near the bottom is double layered. It was arranged as follows.

In addition, in order to obtain the desired thickness, 3 layers, 4 layers, etc.
It goes without saying that it is also possible to use multiple methods.

FIG. 11 is a third example, in which the narrow side and the bottom of the blood chamber are desired to be made thinner at the same time.
5 with insulation material placed near the narrow side and bottom, 1st
Figure 2 is a fourth example in which only the narrow-area sides of the blood chamber are thinned, and Figure 13 is a case in which both narrow-area sides and the bottom of the blood chamber are thinned, and the bottom is intended to be made even thinner. The fifth example of the case is 0. Although the above five cases have been described, the present invention is not limited to the case of bulging, and the point is to place a heat insulating material in the part where the blood chamber is desired to be made thinner and then mold the blood chamber.

The heat insulating material used in the present invention needs to be in close contact with the mold as liquid-tight as possible.

As for the material of the heat insulating material, any material that essentially has heat insulating properties can be used, but it must be able to withstand the temperature of slush molding. Examples include synthetic polymers. For example, so-called engineering resins such as polybimol, polyvinylidene chloride, polyethylene terephthalate, nylon 6, and nylon 66, polycarbonate, polysulfone, acrylic resin, polyacetal resin, A-rssfa4 resin, hard rubber such as ebonite, polyurethane, epoxy resin, etc. It may also be an inorganic insulating phase such as fired carbon or ceramics, natural wood, asbestos cement, or the like.

These heat insulating materials may be molded integrally with the mold, but it is preferable to make them removable from the mold so that the desired insulating material can be freely replaced and used.

The wall thickness of the blood chamber to be molded depends on the PV used.
Although it varies depending on the amount of bilebilizer in O, it is usually 11111-3.
However, the thickness of the partially thinned portion according to the present invention is 0.311 m to 1111 m! Preferably, it is formed of I. If it is less than 0.3 n, the strength will be poor, and if it is more than 1 n, that part will preferentially become stiff and the object of the present invention will not be achieved.

In the case of the present invention, since the upper lid part is molded separately in advance, it is preferable that the amount of plasticizer in the upper lid part be smaller than the amount of plasticizer in the blood chamber part. Therefore, when the upper part is molded from polyvinyl chloride plastisol, the polyvinyl chloride plastisol contains relatively little plasticizer, for example, 100 parts of polyvinyl chloride and 40 to 60 parts of dioctyl phthalate (plasticizer).
As a stabilizer, a plastisol consisting of 3 parts of a calcium-zinc organic complex is preferred.10,000 The blood chamber is a part whose volume changes when driven by air, and which performs pump operation, so it is soft and elastic. There is a need. A suitable composition of plastisol is preferably 60 to 90 parts of dioctyl phthalate per 100 parts of polyvinyl chloride.

Furthermore, it is also possible to use a top lid made of hard polyvinyl chloride to which no plasticizer is added, or to use a top lid made of another polymeric material to which the top lid and blood chamber can be bonded using the method of the present invention. is also possible. In this case, the polymer materials used include polyurethane, epoxy resin, and polymethyl methacrylate resin. The upper lid part made of these polymeric materials can be fused and bonded to the blood chamber part made of soft polyvinyl chloride by the method shown in the present invention.

The interior of the integrally molded blood pump can be coated with a known antithrombotic material, such as a polyurethane-dimethylsiloxane block copolymer, to improve the antithrombotic properties of the blood contacting surface.

The form of the blood chamber of the blood pump in the present invention is as follows:
The flat shape illustrated in FIG. 2 may be used, and the ratio D/W of the maximum thickness of the blood chamber 2 to the maximum thickness W in the unloaded state shown in FIG. 3 is 15 to 50, preferably 1. 6～
2.5, more preferably 1.8 to 2.3.

Further, it is preferable that there is a ratio of 0.8≦D/L≦2.0 between the total height on the center line of the blood chamber 2 and the maximum height.

In a blood chamber that satisfies these conditions, the pattern of crushing due to air pressure can be made constant for each beat.

Examples Examples 1 to 3 and Comparative Examples The upper lid shown in FIG. 7 was made of polyvinyl chloride containing 70 parts by weight of DOP (based on 100 parts by weight of polyvinyl chloride), and then a mold was formed as shown in FIG. The cap was fluid-tightly attached to the cylindrical portion of the upper lid. The mold includes (1) a heat insulating material made of soft polyvinyl chloride with a thickness of 151 Im in the lower half of the mold as shown in FIG. A heat insulating material made of soft polyvinyl chloride with a thickness of 5.0111 mm is placed near the bottom with the same thickness as in (1) above,
(3) As shown in FIG. 12, a heat insulating material made of soft polyvinyl chloride having the same thickness as 111 above was attached to the narrow side surface of the mold. Then, from the blood introduction tube as shown in Figure 8 (BL)
Polyvinyl chloride plastisol containing 80 parts by weight of DOP was introduced into each part up to a position in contact with the upper lid part.

Next, these molds were immersed in a 130°C heating bath for 2 minutes,
The plastisol was then discharged as shown in FIG. 8(D). Through this discharge process, the boundary between the adhesive part of the heat insulating material and the part containing only the mold is formed into a tapered shape with no step at all due to the natural flow of plastisol. After evacuation, the insulation was removed and the mold was heated at 190°C for 20 minutes.

Thereafter, when the mold was cooled to room temperature and the mold was removed, the upper lid part and the blood chamber part as shown in FIG. 8 (Fl) and FIG. 1 were integrally and seamlessly formed.

In addition, the wall thickness of the molded blood chamber in the part where the insulation material is not placed (excluding the tapered part at the border where the insulation material is placed) is +11, (21
, +31 are both 1.7 dragons, and the thickness of the thinnest part made thin by placing insulation material is 11112wIm, (2)
1.2 The bottom with double roof and insulation material is (L8), (3
)13111.

By the way, the maximum width D of the blood chamber (shown in Figure 2)
is 60m1L as shown in Figure 3, the maximum thickness W is 25111
, therefore D/WFi2.4, and the total height L (shown in Figure 2) on the center line of the blood chamber was 6011 m, and D/L id, to.

As a comparative example, the upper lid part and the blood chamber part without the thin-walled part were seamlessly and integrally formed in the same manner as in the example except that no heat insulating material was provided.

The blood chambers of the three Examples and the Comparative Example were housed in an outer case 1 as shown in FIG. 1, and the upper lid portion and the outer case were brought into close contact. In addition, blood introduction pipe and discharge pipe 3
, 4 are each loaded with valves 6 and 7 to form a blood pump,
When these blood pumps were used in goats to carry out cardiac assistance experiments using left heart bypass at a rate of 15//n+in for 44 days, no thrombus was observed in the blood chamber of this example. The stroke volumes of the pumps used were all sod. For comparison, the same experiment was conducted using the blood pump without the wall thickness taper of the present invention, and in order to prevent thrombus from forming for 30 days,
When the blood was pulsated for 7 days at a stroke volume smaller than that, for example, 1.517 m1n, which is the same as in the example, a thrombus was generated at the bottom of the sac-shaped blood chamber. In addition,
The stroke volume of the blood pump used was also 50
-It was.

Effects of the Invention One of the features of the present invention is that when the volume of the blood chamber is reduced by compression, the reduction occurs from the vicinity of the bottom. The reason is that it is made thinner than it is thick.

Still another feature of the present invention is that when the volume of the blood chamber is reduced due to compression, the reduction occurs from near the bottom, and as the volume decreases, both sides of the blood chamber are crushed to ensure tight contact. The reason is that the wall thickness of the narrow-area side surface is thinner than that of the other parts.

Although the present invention may be applied to aqueous plastisols, it goes without saying that it is also applicable to organosols in which the dispersion medium is an organic solvent.

The present invention is based on a completely new idea and makes it possible to freely taper the ideal membrane thickness of the blood chamber. This is of great significance as it has brought about great progress in preventing the formation of thrombi by improving the flow of blood to avoid stagnation.

[Brief explanation of drawings]

Fig. 1 is an exploded perspective view of the sac-type blood pump, Fig. 2 is a front longitudinal cross-sectional view of the upper lid and blood chamber, Fig. 3 is a side longitudinal cross-sectional view, and Fig. 4 is a cross-sectional view of the blood chamber. , Fig. 5, (B), (((ri) is a side longitudinal cross-sectional view showing in order the volume reduction and expansion changes of the blood chamber shown in Fig. 2, and Fig. 6 is a cross-sectional view taken along the line X-X in Fig. 5B. figure,
Fig. 7 is a perspective view of the upper lid, Fig. 8 (N-('F) is an explanatory diagram showing the forming process of the blood chamber, and Fig. 9-13 is a perspective view of the upper lid part. It is an explanatory view showing an example in which a blood chamber is formed by using the same method. In the figure, numeral 1 is an outer case, 2 is a blood chamber,
Reference numeral 5 indicates an upper lid, 15 indicates a mold, and 16 indicates a heat insulating material. Patent Applicant: Zeon Co., Ltd. Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 (A) (B) (C) Figure 6 c-11 Figure 7

Claims (1)

[Claims] 1. A container-shaped mold is liquid-tightly attached to an upper lid having a blood inlet tube and a blood discharge tube, and polyvinyl chloride plastisol is added into the mold to the extent that it contacts the upper lid, and then the gold is poured into the mold. A slush molding method in which a blood chamber is integrally molded by heat transfer from the outside of the mold, characterized in that a heat insulating material is arranged on the outside of the mold, and at least a part of the blood chamber is thinned into a tapered shape. How to mold a blood pump◇